Coupled modeling of Excavation Damaged Zone in Boom clay: Strain localization in rock and distribution of contact pressure on the gallery’s lining

Abstract

a b s t r a c tAround galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for high-level radioactive waste, the resulting change in the host rock properties in this damaged zone may potentially be important with respect to the long-term evolution and the performance of that system. In this context, predicting the extent of the so-called Excavation Damaged Zone (EDZ) and, possibly, the fractures' network topology remains a challenge. This study is aimed to simulate numerically the extension of this zone at the large scale's excavation, around the Connecting gallery (HADES URL, Mol, Belgium), in Boom clay host rock through analyzing the evolution of strain localization in shear bands mode. To realistically model the involved phenomena, the concrete lining is considered on the gallery wall highlighting its impacts on the evolution of convergence and EDZ around the gallery. The focus of the current paper is made on analyzing the coupled hydro-mechanical behavior of Boom clay host rock during and after the gallery excavation with respect to the evolution of localized shear bands around the gallery. This study is accompanied by the analysis of the contact mechanism on the interface between the clay massive and the lining. The obtained results reveal some interesting features regarding the contact phenomenon relatively to the evolution pattern of shear bands within the clay around the gallery. To assess the reliability of the proposed approach, a discussion on some in-situ observations during the gallery's construction is also performed based on which a good agreement is found between the in-situ evidence and simulated results.

Shear banding modelling in cross-anisotropic rocks

“…Previous numerical studies indicate that for an isotropic triggering of strain localisation and to the creation of the excavation fractured zone during the drilling Pardoen et al, 2015a;Salehnia et al, 2015). Moreover, this fractured zone has an elliptical extension with a significantly larger extent in one direction, depending on the stress anisotropy.…”

Permeability evolution and water transfer in the excavation damaged zone of a ventilated gallery

“…In this work, we propose to represent 275 the fractures around galleries with shear strain localisation [29,30,31], which requires an appropriate numerical method to avoid mesh dependency. In fact, a pathological problem of mesh dependency is inherent to strain localisation modelling with classical finite element methods [32,33].…”

Analysis of Internal Stress Distribution and Mechanics Characteristics of Pre-existing Cavity in Brittle Rock Under Triaxial Cyclic Loading

“…In the process of rock mass excavation and mineral mining (Yang et al, 2017;Wang et al, 2019;Zhang et al, 2019;Zhao et al, 2019b), an excavation damage zone will be formed in the surrounding rock within a certain range of the cave (Salehnia et al, 2015). In order to provide a theoretical basis for the stability and safety of rock masses in engineering contexts, physical experiments and scanning electron microscopy (SEM), Computed Tomography (CT), Acoustic emission (AE), and numerical simulation have been carried out on artificial jointed rock (Zhao et al, 2017b;Peng et al, 2019b;Zhao et al, 2019a) or rock-like materials (Zhao et al, 2016;Lin et al, 2019a).…”